Molecular Mechanisms in Ischemia The central theme of this program project is that cerebral ischemia alters the expression of gene products that help to determine whether ischemic neurons live or die. The scientific goals are to identify these gene products, and by modifying their expression, to modify the outcome of cerebral ischemia. The rational for this approach is the increasing understanding that cell death, including neuronal death from ischemia, is an active, evolving process that involves new protein synthesis. Identifying gene products that determine the fate of ischemic neurons would have major significance in increasing understanding of the pathophysiology of ischemic neural injury and in pointing the way toward new therapeutic approaches to stroke and related disorders. For example, the discovery that expression of a deleterious gene product is increase in ischemia could lead to treatment aimed at blocking its expression or action, while the finding that a gene produce is neuroprotective in ischemia would prompt efforts to enhance its expression or pharmacologically mimic its effects. The strategy for achieving our objectives is to use state-of-the-art molecular and cellular techniques to identify gene products whose expression is altered in brain regions preferentially sensitive and preferentially resistant to global cerebral ischemia, and in brain rendered tolerant to ischemia by prior exposure to a sub lethal ischemic insult, and in vivo rat models of cerebral ischemia (Project 1). In vitro cell culture models of neuronal ischemia and neuronal cell death will then be used to investigate the functional significance of these gene products, by assessing whether modifying their expression with antisense oligodeoxynucleotides or viral vector-mediated gene transfer also modifies neuronal death (Project 2). The most promising candidate neurocidal and neuroprotective gene products that emerge from Projects 1 and 2 will then be evaluated further by antisense techniques and gene transfer in vivo rat models of cerebral ischemia (Project 3). The Viral Vector Core (Core A) will develop and prepare replication-defective herpes simplex viral vectors for the gene transfer studies proposed in Projects 2 and 3. The Administrative Core (Core B) will provide clerical assistance, meeting arrangements, centralized ordering, grant management, and statistical and scientific consultation through internal and external advisory boards.